Basic build =

Add reverse polarity protection - A fuse in series with your circuit & a diode in parallel (read about power protection circuits)

Connect leads to battery clips

Connect Clear modem to Wifi AP

Notes on Clear

Clear customer service sticks to a script, out of the ordinary requests will result in you being transferred from person to person and possibly denied. If you find yourself stuck, or they won't activate your used modem message @clear on Twitter --- reps there provide fast, competent resolution.

In addition to monthly service Clear offers mostly unadvertised $10/day, $25/week passes, which may be more economical if you are only using the device for events.